63 



the error of defect in the one case being one-haK the error of excess in the other. The 

 second formula ha» also another advantage for whieli it is to be preferred. The 

 ordinary modes of measurement and calculation give, as a rule, too high a fi^re for 

 ilie sectional area concerned in each case. The excess is partly ojmpensated by the' 

 employment of the second Formula ; whereas the use of the first woiud only exagge- 

 rate it. In order still further to diminish error, long logs should be measured in two 

 or more sections, the number of the sections increasing, i.e., their length diminishing, 

 with the taper of each log. The contents of logs of re;;ular shape and not exceeding 

 20 feet in length may, however, be deduced from their sectional area in the middle. 

 Longer logs, even if of regular shape, should be cubed in two or three sestiong. All 

 large round logs should be measured singly. If the logs are stacked so that they 

 'Cannot be conveniently measured in the middle, the msan of the sectional areas at the 

 base and at the top must be taken. The mean sectional area should not, under any 

 -circumstances, be deduced from the mean of the diarnaters at the two extremities, 

 respectively, or an error of from 10 to 15 per cent, may result. Poles are seldom 

 cubed siiiply ; but nearly always in stacks, built up of poles of one and the same 

 length and of approximately the same diameter. Their solid contents are generally 

 fiscertained by inspection from special tables. Straight and regularly-shaped branches 

 are measured in the same way as logs. 



It must be ofcserved, however, that while diameter measurements give more nearly 

 the actual contents of lo^s and trees, yet in practice the contents of round timber 

 are always calculated, for trade purpoi^es in India and in England, on the assumption 

 that the sectional area is arrived at by squaring the quarter girth. 



The solid contents of small pieces, toppings and loppings, and irregular-shaped 

 pieces from trtmnps and routs are obtainable by the water method (their volume 

 being equal to the quantity of water they displace when submerged), or by the 

 •water-method and weighment combined. For the water-method special vessels, called 

 xylometers. may be employed. In the combined system, samples of each kind or 

 class of wood are successively weighed and measured by the water-method, and the 

 -contents of the entire quantity in each class are then worked out by means of simple 

 proportion. Figures exprexsing specific gravity cannot be employed ; since the 

 specific gravity of wood varies, not only according to the amount of moisture present 

 bnt, even in one and the same tree, according to the part from which the wood has 

 been derived. ' 



The most rapid way of measuring small wood on a large scale is to stack it, oat 

 up into billets of the same length, the width of each stack being equal to the length 

 «t the billets. The contents of a stack will be equal to length x height X common 

 length of the billets. The length of a stack built up on a slope must be measured 

 hoiizontally. The above formula will give us only stacked contents. To reduce the 

 Jatter to solid contents, we must determine, by the water method or by the combined 

 water and weighment method, the exact volume of a sufSeiently large number of 

 «tacked nnits, thereby obtaining the ratio between solid contents and stacked con- 

 tents. T'> obtain the solid contents of a stack it ia then necessary merely t» multiply 

 the stacked contents by this ratio which may be termed the reducing factor.* 



In connection with the determination of the solid contents of stacked wood it is 

 obvious : — 



{a) That the longer the billets or the less carefully built up the stacks, the 

 less will be the salid contents. In careless stacking, billets of ten lie 

 across one another. 



(i) That the thicker or more regular-shaped the billets, or the more carefully 

 built lip the stacks, the greater will be the solid contents. 



(c) That the larger the stacks, the greater will, be the reducing factor. 



When barjc is si)ld sepirately its quantity may be defcerioiued either by weigh- 

 ment or by ascertaining the volume. The solid contents are calculated by redu'dng 



* the following figm-es may be accepted as average lactois lor converting etacl^ed iato EOlid 

 'Contents :— 



Split wood 0-65 to 0'83 



Boo d ' lllets (lsr?e) 060 to 0-6S 



Ditto (niedinm) ... ..■...,. 0-30 to 0-60 

 Small stuff, itumpti and roots 0-16 to 0'30 



